Concrete placed on a structure was subsequently cored after 28 days and the following results were obtained of the compressive strengths from five test specimens: 3625, 3750, 3825, 3450 and 4155 psi. Part 1) Determine the 90% two-sided confidence intervals of the mean concrete strength. (Answer correct to 1 decimal places) Lower Limit 3568.2 100% Upper Limit 3953.8 100% Part 2) Suppose the confidence interval established is too wide, and the engineer would like to have a confidence interval +310 psi of the computed sample mean concrete strength. What is the confidence level associated with the specified interval based the five measurements given above?